An embodiment of the present invention relates generally to integrated circuit fabrication. More particularly, an embodiment of the present invention relates to electrical connection technology. In particular, an embodiment of the present invention relates to etching a ball-limiting metallurgy in the presence of lead, tin, and copper.
Electrical bump connectors such as metal bumps or balls are used in flip-chip (C4) applications. As the progress of miniaturization continues, the junction between a microelectronic device metallization and the electrical bump becomes increasingly large relative to the mass of the electrical bump. Consequently, junction disparities have an increasingly detrimental effect on electrical communication between the device and the electrical bump.
Etching of the metal layer or layers exposes a portion of the metallization pads and often leaves residual titanium on the passivation layer. Etching also mobilizes portions of the metallization pads and redeposits them on the passivation layer. The redeposited metallization pad material and the residual titanium may form stringers or other structures that may lead to electrical test (e-test) failures or field failures.